In merging a larger pool of data, the problem of domain shift arises. Domain shift is one of the most salient problems in medical computer vision [1]}. A model trained on the data from one distribution might yield poor results on the data from the different distribution. In CT imaging, one of the main sources of the domain shift is the difference in reconstruction kernels, the parameter of the Filtered Back Projection (FBP) reconstruction algorithm [2]}. One could perceptually compare the same image reconstructed with two different kernels in Fig. REF , e.g., B1 and B2. For the kernel-caused domain shift, several works have shown the deterioration of the models' quality, in lung cancer segmentation [3]}, and in emphysema segmentation [4]}.
